Ultraviolet Absorption Spectrum of Malonaldehyde in Water Is Dominated by Solvent-Stabilized Conformations

Xuefei Xu, Jingjing Zheng, Donald G Truhlar

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Free energy calculations for eight enol isomers of malonaldehyde (MA) and simulation of the ultraviolet (UV) absorption spectrum in both the gas phase and water (pH = 3, where the molecule exists in neutral undeprotonated form) show that in water the two s-trans nonchelated enol conformers of MA become thermodynamically more stable than the internally hydrogen-bonded ("chelated enol") conformer (CE). The pure CE conformer in water has a slightly red-shifted UV spectrum with respect to that in the gas phase, but the blue-shifted spectrum observed in water at pH 3 is dominated by solvent-stabilized conformations that have negligible populations in the gas phase. Density functional calculations with the solvation model based on density (SMD) and an ensemble-averaged vertical excitation model explain the experimental observations in detail.

Original languageEnglish (US)
Pages (from-to)8026-8029
Number of pages4
JournalJournal of the American Chemical Society
Volume137
Issue number25
DOIs
StatePublished - Jul 1 2015

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